PerformanceEntry.startTime

The startTime property returns the first recorded timestamp of the performance entry.

Note: This feature is available in Web Workers.

The value returned by this property depends on the performance entry's type:

This property is Read only .

Syntax

entry.startTime;

Return value

A DOMHighResTimeStamp representing the first timestamp when the performance entry was created.

Note: if the performance entry has an entryType of "resource" (i.e. the entry is a PerformanceResourceTiming object), this property returns the PerformanceEntry.fetchStart timestamp.

Example

The following example shows the use of the startTime property.

function run_PerformanceEntry() {
  log("PerformanceEntry support ...");

  if (performance.mark === undefined) {
    log("... performance.mark Not supported");
    return;
  }

  // Create some performance entries via the mark() method
  performance.mark("Begin");
  do_work(50000);
  performance.mark("End");

  // Use getEntries() to iterate through the each entry
  var p = performance.getEntries();
  for (var i=0; i < p.length; i++) {
    log("Entry[" + i + "]");
    check_PerformanceEntry(p[i]);
  }
}
function check_PerformanceEntry(obj) {
  var properties = ["name", "entryType", "startTime", "duration"];
  var methods = ["toJSON"];

  for (var i=0; i < properties.length; i++) {
    // check each property
    var supported = properties[i] in obj;
    if (supported)
      log("..." + properties[i] + " = " + obj[properties[i]]);
    else 
      log("..." + properties[i] + " = Not supported");
  }
  for (var i=0; i < methods.length; i++) {
    // check each method
    var supported = typeof obj[methods[i]] == "function";
    if (supported) {
      var js = obj[methods[i]]();
      log("..." + methods[i] + "() = " + JSON.stringify(js));
    } else {
      log("..." + methods[i] + " = Not supported");
    }
  }
}

Specifications

Specification Status Comment
Performance Timeline Level 2
The definition of 'startTime' in that specification.
Candidate Recommendation  
Performance Timeline
The definition of 'startTime' in that specification.
Recommendation Initial definition.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support Yes Yes Yes Yes Yes No
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes Yes Yes25 Yes No ?

Document Tags and Contributors

Contributors to this page: fscholz, chrisdavidmills, jpmedley, abbycar, rolfedh, AFBarstow
Last updated by: fscholz,